Photographic processing apparatus

ABSTRACT

This disclosure involves a photographic processing tank designed to develop large size photographs in a compact device employing a minimum volume of standard photographic reagents. The disclosure involves a tubular tank with removable end cap or caps and a porous inner liner which is unaffected by reagents and exhibits non-capillarity and non-wetting characteristics. The liner is flexible so that it may be rolled up against the light sensitive emulsion side of printing paper without damage thereto. The tank holds the reagents and the porous liner spaces the paper while allowing the rapid flow and circulation of reagents through the entire contents of the tube and in intimate contact with all areas of the emulsion. Any and all standard photographic chemicals may be used with this invention.

United States Patent Maxwell 1 1 July 4, 1972 [54] PHOTOGRAPHIC PROCESSING 2,947,236 8/1960 Siegel ..95/93 APPARATUS 1,156,922 10/1915 Nasief et a1 ..95/905 [72] Inventor: Hugh W. Maxwell, 999 East Valley Boulevard, Apt. 6, Alhambra, Calif. 91801 [22] Filed: June 22, 1970 [21] Appl. No.: 48,392

[52] US. Cl. ..95/89 R, 95/93 [51] Int. Cl. ..G03d 3/00 [58] Field oiSeareh ..95/89,90.5,93,100;96/87 [56] References Cited UNITED STATES PATENTS 3,381,599 5/1968 Banks ..95/93 X 3,503,319 3/1970 Buechner ..95/100 3,235,381 2/1966 Field et a1. ..96/40 X 3,516,834 6/1970 Audran et al7 ..96/87 X 2,943,555 7/1960 Hill 95/100 X 1,033,772 7/1912 lnghram... ..95/89 1,624,586 4/ l 927 Czako 95/ 100 3,330,196 7/1967 Chen et al.... ..95/89 1,853,553 4/1932 Davidge ..95/100 EMULSION Primary Examiner-John M. Horan Assistant Examiner-Alan A. Mathews Attorney-John E. Wagner [5 7] ABSTRACT This disclosure involves a photographic processing tank designed to develop large size photographs in a compact device employing a minimum volume of standard photographic reagents. The disclosure involves a tubular tank with removable end cap or caps and a porous inner liner which is unaffected by reagents and exhibits non-capillarity and nonwetting characteristics. The liner is flexible so that it may he rolled up against the light sensitive emulsion side of printing paper without damage thereto.

The tank holds the reagents and the porous liner spaces the paper while allowing the rapid flow and circulation of reagents through the entire contents of the tube and in intimate contact with all areas of the emulsion.

Any and all standard photographic chemicals may be used with this invention.

3 Claims, 8 Drawing Figures PATENTEDJUL 4 m2 FIG. I

EMULSION A FIC5.4

FIGQ? -PAPER (EMULSION SIDE INWARD) INVENTOR HUGH MAXWELL BACKGROUND OF THE INVENTION The processing of large size photographic prints (30 X 40 inches or larger) has heretofore been accomplished primarily in professional photographic processing houses employing large tanks and drums. The amateur home photographer or professional photographer without complex processing equipment has been unable to obtain high quality prints. Many people have attempted to produce large prints 30 X 40 inches by employing a bath tub as a processing tank. This requires a large volume of reagents and produces untidy working conditions. Since only one container is available, reagents must be emptied down the drain and replaced by the succeeding reagent. This slow process usually produces discouraging results.

Another method for producing large size prints is to lay the paper on a chemical-proof floor and swab the reagents on with a sponge or mop. Uniform development is difficult and, again, the results are unpredictable.

These foregoing attempts at large scale printing have caused frustration to the amateur photographer since virtually every home enlarger is capable of projecting an image on a floor or wall suitable for printing if only some means for developing the exposed paper could be accomplished.

In the field of photographic negative development, there have been long tubular tanks with stick-like film holders allowing the processing of film in small amounts of solution. None of these tank arrangements are adapted to printing of large prints.

BRIEF STATEMENT OF THE INVENTION This invention involves basically a tubular tank having at leastone end removable to allow the insertion of a rolled up sheet of photographic printing paper, a cap for sealing and a novel separator to maintain turns of the printing paper apart to allow the free flow of developing reagents and the contact of all areas of light sensitive emulsion on the paper. The separator is highly porous, flexible and, most significant, is unaffected by, non-absorbent of, and non-wetting by any printing reagents.

BRIEF DESCRIPTION OF THE DRAWINGS This invention may be more clearly understood from the following detailed description and by reference to the drawings in which:

FIG. I is a perspective view of a printing tank of this inventron;

FIG. 2 is an enlarged fragmentary view of the separator of this invention;

FIG. 3 is a perspective view of the tank assembly, including a sheet of printing paper in the process of folding for insertion in the tank;

FIG. 4 is an end view of the printing paper-separator combination of FIG. 3 in a rolled condition;

FIG. 5 is a view of the rolled paper-separator combination being inserted in the printing tank;

FIG. 6 shows the filling of the tank with a processing reagent;

FIG. 7 is a view of the processing tank of this invention in the hands of the user during the agitation period; and,

FIG. 8 is an enlarged end view of a non-folded rolled paper separator assembly in accordance with this invention, which is a variation of FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION Now referring to FIG. 1, the tank of this invention is basically a closed end plastic tube 10 which may be either opaque, translucent, or transparent, having sufficient length to accommodate the lesser dimension of the print size to be processed. The tube may be virtually any material which is chemically resistant to the reagents used in developing of photographic emulsion.

Transparent butyrate has been found to be perfectly satisfactory as a material in tubing form with a wall thickness in the order of one-sixteenth inch. Such a thickness provides sufficient stiffness without undue weight. The diameter of the tube varies again with the size of the print to be produced and below is the tabulation of the preferred tube sizes for each of a number of print sizes:

Larger sizes are possible.

The ends of the tube are closed by end caps 11 and 12, one of which may be permanently affixed to the tube and the other must be removable. The end caps 1 1 and 12 must form watertight seals to prevent leakage of the reagent during processing. The caps or seals 11 and 12 preferably are of plastic, non-absorbing material which again is unaffected by processing reagents. Organic cork material is not recommended because of its liquid absorption and retention characteristics.

The tank itself has a relatively small volume as compared with any other known developing device for the size of print to be processed. For example, a tank of 2% X 36 inch dimensions, designed to process prints up to 30 X 40 inch in size, requires only one quart of developer. Even smaller quantities of developing reagents may be used with satisfactory results.

A critical element of this invention is shown in FIG. 2. It is a porous open cell plastic foam liner sheet 13 having a substantial thickness in the order of one-eighth inch and 3 percent material to 97 percent open space. The liner sheet 13 is flexible and exhibits a high degree of resilience while at the same time is non-absorbent. In practice, the material known as open cell polyurethane foam produced by the Scott Paper Company is recommended. The liner I3 contains no pockets or interstices which would tend to hold the reagents. In general, its mesh appears to have a number of hexagonal openings 14 and 15, for example, made up exclusively of obtuse angle intersecting fibers. There appear to be no pockets of any type among the individual fibers for retention of fluid. The surface exhibits a noticeable shiny finish to each fiber, which may in part be responsible for the materials apparent non-wetting characteristic. The liner 13 itself need only be half the size of the print to be produced, since the paper may be folded double and maintained effectively spaced apart by the thickness of the liner 13.

This is illustrated in FIG. 3. In that case, a large sheet of photographic printing paper 16 is shown ready to be folded double about the middle of its longer dimension over the liner 13 of half the paper size. The liner 13 is in contact with the exposed emulsion side of the paper. After the paper is folded over, as indicated by the arrows in FIG. 3, it is in condition to be rolled, with the liner, starting from the folded edge, to form a cylinder small enough to be inserted into the tube 10 when cap I] is removed. The end view of the paper-liner assembly of FIG. 3 is shown in FIG. 4. There it is quite clear that all emulsion surfaces of the paper are separated, with only the non-emulsion sides in contact with each other.

FIG. 5 shows clearly the roll of paper and liner being slid into the open end tube. Thereafter, the reagents are poured into the open end of the tube. The end cap is then replaced, and the tube gently rocked from end to end and rolled from time to time in order to insure constant change of developing liquid over the surface of the emulsion. The linear exhibiting extremely small material to open space ratio allows the developing reagents to come in contact with all of the emulsion. Experience has shown that the emulsion surface in direct contact with the liner shows no effect from this contact. Print quality produced with this invention is as good or better than with any other processing method or device.

Processing of the print occurs using the same procedural steps as employed in conventional development, including the sequential application of developer followed by a stop bath, hypo fixerahardener, hypo eliminator, and wash. With each reagent, the same procedural step is followed, with the used reagent poured out into its storage container. The tank of this invention as indicated requires only a minimum quantity of the reagents. With the easy flow of the solution through the open cells of the liner, it has been found that highest quality prints may be obtained.

It is apparent that the liner 13 is of critical importance to this invention. Specifically, it must have sufficient porosity to allow the free flow of reagents and have no interstices to collect reagents during each step, which otherwise would result in contamination and loss of control of the process. A number of mesh type materials were tried with varying degrees of success. Absorbent paper toweling proved to be valueless because of its high absorbent and retention of reagents. Nylon netting sometimes is satisfactory, but is unpredictable since it tends to produce overdevelopment directly under strands in contact with the emulsion due to its apparent wetting or capillarity.

Various woven cloths and plastics of both absorbent and non-absorbent type produced mixed results, while felt and plush-type cloth materials were unsatisfactory due again to excessive reagent retention. The foam mesh in accordance with this invention is the only one which has never produced a failure in experimental tests. lts non-wetting, non-capillarity characteristics appear to be important. Additionally, the high percentage of open volume as compared to the material allows the free flow of reagents, longitudinally, through the mass and transverse through adjacent sides without restriction. Each cell is open and in communication with at least one other cell so there are no dead pockets. The void percentage of the total volume is approximately 97 percent in the preferred embodiment. The cell or pore size is significant as well. Cells having major dimensions (e.g., diameter) of less than one-thirtieth inch have been found to retain reagents while larger cell mesh, such as, one-tenth inch major dimension, are found to provide more reliable reagent dispersion and flow and therefore are preferred.

As indicated above, the double folding arrangement as shown in FIGS. 3 and 4 is desirable for large prints to avoid an extremely large liner, but it is recognized that often for smaller prints, the printing paper need not be folded and the liner covering virtually the entire face of the print and even extending beyond the edges of the printing paper may be rolled up in a single roll arrangement with the liner exposed to the emulsion side of the paper. This arrangement is shown in end view in FIG. 8.

The foregoing description is merely illustrative of the principles of this invention and shall not be considered as limiting. Instead, the patent monopoly granted for this invention shall not be limited to the specific embodiment shown but rather to the invention as defined below in the following claims.

I claim:

1. An apparatus for developing large size photographic prints comprising:

a tube having a length slightly greater than one dimension of a photographic print to be processed and an inside transverse dimension in the order of 8 to 18 percent of the second dimension of the photographic print to be processed; end closures for said tube; and a thin liner of porous material in the order of 97 percent void, and unaffected by photographic reagents used in processing prints and non-wetted thereby;

said liner being flexible to allow its insertion into the tube as the spacer between adjacent portions of the print to be processed; said liner substantially entirely open cell with each cell opening directly or indirectly with outside surfaces;

said liner characterized by the absence of a significant number of restricted portions or acute angle fiber intersections whereby processing liquids may pass freely in all directions throtcrigh said lin er when said tube is rocked from end to en and said lrner does not entrain any significant quantity of processing fluids when the tube is drained.

2. The combination in accordance with claim 1 wherein said liner comprises open cell polyurethane mesh.

3. The combination in accordance with claim 1 wherein said liner comprises a planar sheet of open cell plastic foam having cells in the order of at least one-thirtieth inch in major dimension and characterized by individual fibers having substantially all intersections at obtuse angles. 

1. An apparatus for developing large size photographic prints comprising: a tube having a length slightly greater than one dimension of a photographic print to be processed and an inside transverse dimension in the order of 8 to 18 percent of the second dimension of the photographic print to be processed; end closures for said tube; and a thin liner of porous material in the order of 97 percent void, and unaffected by photographic reagents used in processing prints and non-wetted thereby; said liner being flexible to allow its insertion into the tube as the spacer between adjacent portions of the print to be processed; said liner substantially entirely open cell with each cell opening directly or indirectly with outside surfaces; said liner characterized by the absence of a significant number of restricted portions or acute angle fiber intersections whereby processing liquids may pass freely in all directions through said liner when said tube is rocked from end to end and said liner does not entrain any significant quantity of processing fluids when the tube is drained.
 2. The combination in accordance with claim 1 wherein said liner comprises open cell polyurethane mesh.
 3. The combination in accordance with claim 1 wherein said liner comprises a planar sheet of open cell plastic foam having cells in the order of at least one-thirtieth inch in major dimension and characterized by individual fibers having substantially all intersections at obtuse angles. 